Electric fuel injection control system for internal combustion engines

ABSTRACT

In internal combustion engines, where the fuel injection valves are electromagnetically operated, at the time of engine acceleration the amount of fuel injected is increased by converting sudden changes in such parameters as the negative pressure in the engine intake manifold into corresponding changes of the mechanical type, such as by the displacement of a diaphragm, according to which mechanical changes an electric fuel injection control is operated. Thus, a delay time is involved, resulting in an insufficient response characteristic. In the specification, there is disclosed an electric fuel injection system for internal combustion engines, comprising; a means to generate electric signals corresponding to the speed of motion of the throttle of the engine or particularly when the speed of the throttle motion exceeds a predetermined value; and a means to increase the amount of fuel delivered for acceleration by so controlling fuel injection valves upon reception of the signal from the first means.

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Shinoda et a].

SYSTEM FOR INTERNAL COMBUSTION l 193 728 5/1965 German 12382 EA ENGINESy [75] Inventors: Kazuo Shinoda, Toyota; Kunio Primary ExaminerLaur,enceM. Goodridge Endo, Anjo, both of Japan Attorney, Agent, or Firm-Cushman,Darby & [73] Assignees: Toyota Jidosha Kogyo Kabushiki Cushman Kaisha,Toyotacho, Toyota-shi; Nippondenso Co., Ltd., Kariya-shi, [57.] ABSTRACT Aichpken, Japan In internal combustion engines, where the fuel inection valves are electromagnetically operated, at the [22] Flled?8,1972 time of engine acceleration the amount of fuel in [21] Appl 3 3543 jected is increased by converting sudden changes in such parametersas the negative pressure in the engine Related Appllcallo Data intakemanifold into corresponding changes of the me- [63] Continuation-impartof Ser. No. 53,821, Aug. 10, chanical type, such as by the displacementof a dia- 1970. 3.7191176 phragm, according to which mechanical changesan electric fuel injection control is operated. Thus, a ForeignApplication Priority Data delay time is involved, resulting in aninsufficient re- July 29, 1969 Japan 44-59801 sponse characteristic. Inthe specification, there is dis- July 29, 1969 Japan 44-59802 closed anelectric fuel injection system for internal combustion engines,comprising; a means to generate [52] US. Cl.. 123/32 EA, 123/119 R,123/140 MC, electric signals corresponding to the speed of motion123/139 AW of the throttle of the engine or particularly when the [5lInt. Cl. F02d 5/02 speed of the throttle motion exceeds a predetermined[58] Field of Search 123/32 EA, 32 R, 119 R value; and a means toincrease thearnount of fuel delivered for acceleration by so controllingfuel in [56] Ref rences Cited jection valves upon reception of thesignal from the UNITED STATES PATENTS first means- 3,593,692 7/l97lScholl et al 123/32 EA 4 Claims, 3 Drawing Figures P9555 FUEL lM/7'/M//VG PULSE FUEL l/VJ D FOR INTERNAL COMBUSTION ENGINES CROSSREFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of application Ser. No. 53,821 filed July l0, l970now US. Pat. No. 3,179,176.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to improvements in electric fuel injection control systems forinternal combustion engines to provide for effectively increasing theamount of the delivered fuel at the time of acceleration without timedelay.

2. Description of the Prior Art In internal combustion engines havingthe usual electric fuel injection control system capable of increasingthe fuel delivery at the time of acceleration of the engine, suddenchanges of the pressure in the intake manifold of the engine as theresult of the accelerating operation are first mechanically detected bysuch pressure-sensitive mechanisms as a diaphragm as correspondingdisplacements and by the detected signal corresponding to a displacementthe switching elements in an electrical circuit are controlled to extendthe pulse width of the pulse signal fed to the injector valves so as tocorrespondingly prolong the open-position time of the injector valves,thereby increasing the fuel amount delivered at the time ofacceleration.

Therefore, with the conventional system of this type a time delay isinvolved from the instant of actuating the accelerating means, forinstance, upon depressing the accelerator pedal, until the increasedfuel delivery actually results, during which delay time the pressure inthe intake manifold first changes, the change in this pressure is thendetected as a displacement of the mechanical means and thereafter thedetection signal corresponding to the displacement drives the switchingelements, so that the response time is very inferior. So long as theabove response steps are involved, it is extremely difficult to improvethe response time by any means available at present. Thus, the aboveconventional system is disadvantageously incapable of exactly followingthe demand of the engine for an increased fuel supply at the time ofacceleration Without delay, so that it cannot fully achieve the intendedobject.

In another aspect, the operating point, at which the function ofincreasing the fuel delivery is brought about by detecting theaccelerating operation through the pressure-sensitive mechanism such asa diaphragm for accelerating the engine, substantially depends upon apoint, at which the above pressure-sensitive mechanism such as thediaphragm detecting the sudden change in the engine intake manifoldpressure as the result of the accelerating operation starts to undergomechanical displacement to control the switching elements, and it isfixed as the displacement starting point is determined by structuralfactors in the design such as the dimensions and configuration of thepressure-sensitive mechanism, mechanical constants involved and designspecifications. Therefore, if the afore-mentioned operating point tobring about the action of increasing the fuel delivery for theacceleration of the engine is to be changed, the design specificationfor the pressuresensitive mechanism such as the diaphragm should befundamentally changed, which is extremely disadvantageous, as well asproviding no compatibility with engines having different ratings.

SUMMARY OF THE INVENTION An object of the invention is to provide anelectric fuel injection control system for use in internal combustionengines, where injector valves are controlled by an electric controlsystem in accordance with an operating parameter for the engine, therebybeing capable of increasing the amount of fuel delivered at the time ofaccelerating the engine without time delay.

Another object of the invention is to provide an elec tric fuelinjection control system for use in internal combustion engines, whichenables readily changing the operating point to bring about the actionof increasing the fuel delivery for the acceleration of the engine andprovides compatibility with engines of different ratings.

According to the invention, there is provided an electric fuel injectioncontrol system for internal combustion engines comprising a means togenerate an electric signal derived from the action of the throttle or amovable part associated with the throttle valve of the engine when thespeed of motion of the throttle in the direction of opening thereofexceeds a predetermined value, and a means to control injection valvesto increase the amount of fuel delivery in response to the electricsignal from the first means, whereby said control system is capable ofmeeting the requirements of the engine characteristics to increase thefuel delivery at the time of acceleration with good response, readilychanging the operating point to bring about the action of increasing thefuel delivery for the acceleration of the engine as well as affordingcompatibility with engines of different ratings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic block diagram ofan embodiment of the electric fuel injection control system according tothe invention.

FIG. 2 is a circuit diagram of the embodiment of FIG. 1

bodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now bedescribed in conjunction with preferred embodiments thereof withreference to the accompanying drawing.

Referring to FIG. 1, which shows an embodiment of the invention, thereare shown fuel injection valves 1 to 4, which are electromagneticallyoperated and provided in respective first to forth cylinders (I) to(IV). shown). Numeral designates a pressure detector to detect thepressure in the intake manifold, which is one of the operatingparameters of the engine, as a corresponding DC voltage. The outputvoltage from the pressure detector 105 is amplified by an amplifier 106.Numeral 107 designates a fuel injection timing detector to generatesignal pulses in synchronism with the timing of the opening of theintake valves of the respective cylinders (I) to (IV) or the fuelinjection timing of the fuel injection valves 1 to 4. The pulses may begenerated as a function of the rotation angle of the cam shaft, for ex-FIG. 3 shows the operating characteristics of the emample. The outputsfrom the amplifier 106 and from the fuel injection timing detector 107are fed to a pulse width modifier 108, which generates fuel injectionpulses synchronous with the output pulse signal from the fuel injectiontiming detector 107 and having a pulse width corresponding to the outputvoltage from the amplifier 106, that is, the pressure in the intakemanifold. A fuel injection valve draining circuit 109 receives the fuelinjection pulse signal from the pulse width modulator 108 and energizesa corresponding one of the fuel injection valves 1 to 4 to hold it inthe open position for a time interval equal to the pulse width, which isproportional to the amount of fuel to be injected. Shown within abroken-line rectangular section 110 is an acceleration fuel-increasesignal generator to generate an electric signal for increasing the fuelsupply for accelerating the engine, which comprises a permanent magnet111 linked to the throttle of the engine or to a movable memberassociated to the throttle, a coil 112 disposed within the magneticfield established by the permanent magnet 111, a diode 113, a capacitor114 and a variable resistor 115. A voltage induced in the coil 112 bythe movement of the predetermined magnet 111 which accompanies therotation of the throttle in the opening direction charges the capacitor114 through the diode 113. 1

It will be appreciated that the voltage induced in the coil 112 is at alevel proportional to the speed of motion of the throttle or the movablepart associated with the throttle. The capacitor 114 is dischargedthrough the variable resistor 115 for a time interval determined by thetime constant of the circuit consisting of the resistor 115 and thecapacitor 114. The voltage on the output terminal 116 of theacceleration fuel-increase signal generator 110, that is, the terminalvoltage across the capacitor 114, is fed in superposition upon thevoltage of the output from the pressure detector 105 to the amplifier106.

Now referring to FIG. 2, which is a circuit diagram of theabovementioned embodiment, the pressure detector 105 comprises an enginevacuum sensor 1051, a diode 1052, a resistor 1053 and a capacitor 1054.The engine vacuum sensor 1051 includes a diaphragm, which is movableresponsive to variation of the pressure in an engine intake manifold(not shown), a moving core which is connected to a movable member fixedto the diaphragm, and a differential transformer having a winding means1055 which is electrically connected to an oscillator 1056 and adaptableto produce a signal voltage depending upon the position of the movablemember relative to the winding means 1055.

The amplifier 106 includes an operational amplifier 1061 whose input isconnected to the outputs of the pressure detector 105 and theacceleration fuel increase signal generator 110. The injection timingdetector 107 includes four identical circuits 107a, 107b, 1076 and 107d,each having a breaker 1071 which opens and closes in synchronism withrotation of the engine, a capacitor 1072 and a transistor 1073. Thepulse width modulator 108 comprises four identical circuits 108a, 108b,1080 and 108d connected to the circuits 1070, 107b, 1070 and 107d,respectively, and each having a saw tooth wave generator 1081 and acomparator 1082. The fuel injection driving circuit 109 comprises alsofour identical circuits 109a, 109b, 1096 and 109d connected to thecircuits 108a, 108b, 1080 and 108d, respectively, and each having a pairof tran- LII sistors 1091 and 1092. Thus the injection timing detector107, the pulse width modulator 108 and the fuel injection drivingcircuit 109 comprises four identical sets of series circuitsrespectively connected to the fuel injection valves 1 to 4. It is notedthat the number of the sets of series circuits corresponds to the numberof engine cylinders.

The operation of this embodiment will now be described in detail withreference to the graphs of FIG. 3, in which the abscissa is commonlytaken for time t, and which shows at (A) the voltage induced in the coil112, at (B) the terminal voltage across the capacitor 114 and at (C) thefuel injection pulses for impression on the individual fuel injectionvalves 1, 3, 4 and 2 provided respectively in the first, third, fourthand second cylinders as indicated respectively from the top downwards at(I), (III), (IV) and (II).

In the normal engine operation with the throttle held at a predeterminednormal position, the permanent magnet 111 assumes a predeterminedposition and does not move, causing no voltage to be induced in the coil112, so that the fuel injection valve driver circuit 109, receivingsuccessive fuel injection pulses generally indicated at P generated bythe pulse width modulator 108, which pulses have a pulse width (asgenerally indicated at T at (C) in FIG. 3) conforming only to the outputvoltage from the pressure detector and which are synchronized with theoutput pulse signal from the fuel injection timing detector 107, drivesthe respective fuel injection valves 1 to 4 in accordance with thecorresponding pulses P,, and holds these valves open for a period equalto the pulse width T during which the fuel is injected, for the normaloperation of the engine conforming to the requirements of the enginecharacteristics under normal driving conditions. The order of driving(fuel injection of) the fuel injection valves depends upon thedistributing function of the fuel injection valve driver circuit 109,and is consistent with the order of firing the cylinders, for instancein the order of first cylinder (I), third cylinder (III), fourthcylinder (IV) and second cylinder (II).

When the permanent magnet 111 moves in accompanyment to the accidentalmovement of the throttle or the movable member associated thereto due tosuch causes as vibration of the engine during the normal engineoperation without any action taken for accelerating the engine, voltageis induced in the coil 112 as indicated at V at (A) in FIG. 3, but suchinduced voltage is at levels lower than the level of the referencevoltage V; determined by the forward voltage drop across the diode 113,so that the capacitor is not charged.

When acceleration is applied to the engine, for instance by depressingthe accelerator pedal, to move the throttle toward the full position,the permanent magnet 111 moves, inducing a voltage in the coil 112 witha maximum level exceeding the reference voltage V as indicated at V at(A) in FIG. 3, thus charging the capacitor 114 through the diode 113, asshown at (B) in FIG. 3. After the operation of opening the throttlevalve is stopped, voltage is no longer induced in the coil 112, and thecharge accumulated on the capacitor 114 is discharged through theresistor 115 within a time determined by the time constant for thecircuit of the parts 114 and 115. As the terminal voltage across thecapacitor 114 is fed in superposition upon the output signal from thepressure detector 105 to the amplifier 106, the output voltage from theamplifier 106 has a component accounting for the terminal voltage acrossthe capacitor 114 charging in accordance with a chargingand-dischargingcharacteristic as indicated at V,, at (B) in FIG. 3 in addition to thecomponent accounting for the output voltage from the negative pressuredetector 105. Accordingly, the pulse width of the fuel injection pulsesP, to P produced by the pulse width modulator 108 during the dischargingof the capacitor 114 vary, as indicated at T, to T at (C) in FIG;

3, in correspondence to the .level of the voltage produced afteramplification of the terminal voltage across the capacitor 114 by theamplifier 106. Thus, the amount of the fuel injected is increased inproportion to the pulse width T, to T thus smoothly accelerate theengine.

After the capacitor 114 is discharged through the resistor 115, thepulse width T of the fuel injection pulse signal from the pulse widthamplifier 108 is again determined solely by the voltage output from thedetector 105.

When quicker or more forceful accelerating action is applied to theengine, a higher voltage exceeding the reference voltage V as indicatedat V, at (A) in FIG. 3, is induced in the coil 112, and a correspondinghigher terminal voltage, as indicated at V, at (B) in FIG. 3, is builtup across the capacitor 114. Accordingly, the pulse widths of the fuelinjection pulses P, to P occurring during a time interval from instantt,,, at which the charging of the capacitor 114 starts, until instantt,, at which the discharging of the capacitor 114 ends, are furtherincreased, as indicated at T, to T at (C) in FIG. 3, in correspondenceto the level of the terminal voltage across the capacitor 114 inaccordance with the charging-and-discharging characteristic of thecapacitor 114. In addition to the increase in the pulse width, thenumber of times the injection of an increased amount of fuel is made, isincreased.

In case the throttle valve is suddenly closed for rapidly deceleratingthe engine, a negative voltage in induced in the coil 112, so that thecapacitor 114 is not charged, thus generating no signal for increasingthe fuel delivery.

The number of times the injection of an increased amount of fuel is mademay be preset to meet the requirements of the engine characteristics bymaking variable at least one of the capacitance of the capacitor 114 andthe resistance of the resistor 115 or by selecting suitable values ofthese quantities. The voltage level to be established for avoidingmalfunctioning of the system due to such causes as vibration of theengine or the operating point to start increasing the fuel delivery foraccelerating the engine, that is, the reference voltage V, in the aboveembodiment, is determined by the forward voltage drop across the singlediode 113. It may as well be preset by a plurality of diodes connectedin series, a constant-voltage diode having a certain breakdown voltage,a transistor and so forth.

Also, in this embodiment only the pressure in the intake manifold, whichis one of the operating parameters of the engine, is used fordetermining the pulse width of the fuel injection pulse signal. Otheroperating parameters such as the engine temperature, atmospherictemperature and pressure may as well be used to modulate the pulse widthof the fuel injection pulse si nal.

As is described, with this embodiment including the accelerationfuel-increase signal generator to generate an electric output signal ata level corresponding to the speed of motion of the throttle or themovable member associated thereto of the engine when such speed exceedsa predetermined value and a means to extend the time, during which thefuel injection valve is open, in accordance with the level of the outputsignal from the acceleration fuel-increase signal generator, it ispossible to increase the fuel delivered with excellent responsecharacteristics.

Also, by the incorporation of a means to gradually decrease the level ofthe output signal from the acceleration fuel-increase signal generatorwith time according to the above embodiment, the amount of the fuel tobe increased and the period and the number of times the injection of theincreased fuel may be so determined as to meet the requirements of theengine characteristics, thus providing for further smoother accelerationof the engine.

This embodiment can also feature the excellent effects that theoperating point to start increasing the fuel delivery may be readilychanged to meet compatibility with engines of different ratings isprovided, and that the malfunctioning due to such causes as vibration ofthe engine is prevented.

The means to obtain an electric output signal corresponding to the speedof motion of the throttle or the movable member associated thereto ofthe engine is not limited to the combination of permanent magnet 111 andcoil 112 as in the preceding first and second embodiments, but othermeans such as a semiconductor element and a magnetostriction element mayalso be used. As the movable member associated with the throttle mayserve an accelerator ring, the accelerator pedal and so forth. Further,though the preceding embodiments are concerned to the four-cylinderengine, the invention may of course be applied to the single cylinderengine and other multi-cylinder engines.

We claim:

1. An electrical fuel injection control system for an internalcombustion engine having electromagnetic means for operating fuelinjection valves of the engine and operative to inject fuel in responseto injection pulses each having a pulse width varying as a function ofparameters indicative of the condition of said engine comprising:

a permanent magnet signal generator having a permanent magnet linked tothe throttle of the engine and an armature coil electromagneticallycoupled with said permanent magnet for producing an output voltageresponsive to the movement of said permanent magnet;

first circuit means connected between said armature coil and secondcircuit means for rectifying said output voltage of said armature coiland supplying a current depending on said rectified output voltage tosaid second circuit means when said output voltage, exceeds apredetermined level;

said second circuit means having a capacitor adaptable to storeelectricity by said current supplied thereto and a resistor adaptable todischarge said stored electricity for producing a voltage variablesignal with discharging of said stored electricity;

pressure signal generating means responsive to the pressure of engineintake manifold of said engine for generating a voltage signalindicative of said pressure;

third circuit means connected to said second circuit means and saidpressure signal generating means and including an operational amplifierto add the signal derived from said second circuit means to the signalderived from said pressure signal gener-- ating means to produce asignal which varies as a function of the superposition of said voltagevariable signal produced by said second circuit means and said voltagesignal of said pressure signal generating means;

fourth circuit means connected to said third circuit means for producinga fuel injection pulse signal whose pulse width is determined by saidsignal produced by said third circuit means;

fifth circuit means connected to said fourth circuit means and saidelectromagnetic means for driving said electromagnetic means for aninterval corresponding to the pulse width of said fuel injection pulsesignal.

2. An electrical fuel injection control system for an internalcombustion engine comprising:

a signal generator having a member movable in response to the operationof the throttle and means responsive to the movement of said member forproducing a first signal voltage indicative of the moving speed of thethrottle;

first circuit means having a rectifier connected to said signalgenerator, a capacitor connected to said rectifier to store electricitysupplied thereto through said rectifier by said first signal voltage ofsaid signal generator, and a variable resistor connected in parallelwith said capacitor for discharging said stored electricity, saidrectifier having a predetermined forward breakdown voltage whereby saidfirst signal voltage is applied to said capacitor only when said signalfirst voltage exceeds said forward breakdown voltage;

means for detecting the condition of the engine for producing a secondsignal voltage indicative of at least one predetermined parameter of thecondition of said engine; means connected to said capacitor of saidsignal generator and said detecting means and including an amplifierhaving an operational amplifier for adding the signal derived from saidsignal generator to the signal derived from said detecting means;

means connected to said operational amplifier for generating a fuelinjection signal whose pulse width is controlled as a function of theaddition by said operational amplifier; and

means connected to said fuel injection pulse signal generating means andhaving electromagnetic valves for injecting fuel into cylinders of theengine in a predetermined sequence for an interval corresponding to saidcontrolled pulse width of said fuel injection pulse signal.

3. An electrical fuel injection control system according to claim 1,wherein said fourth circuit means comprises a saw tooth wave generator.

4. An electrical fuel injection control system according to claim 2,wherein said fuel injection signal generating means comprises a sawtooth wave generator.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P n 3.842.811Dated Qg'me: .22 J 9 7 4.

lnvenmfls) Shinoda et al It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Page 1, line [631, delete "Aug." and insert -.-July--.

Signed and sealed this 4th day of March 1975.

(SEAL) v Attest:

' C. MARSHALL DANN RUTH C. MASON Commissioner of Patents AttestingOfficer and Trademarks FORM PO-IOSO (10-69) USCOMM-DC wan-pea I U S,LOVIRNI UH Hl NI nu OIQIKI II." 0- lit-3N

1. An electrical fuel injection control system for an internalcombustion engine having electromagnetic means for operating fuelinjection valves of the engine and operative to inject fuel in responseto injection pulses each having a pulse width varying as a function ofparameters indicative of the condition of said engine comprising: apermanent magnet signal generator having a permanent magnet linked tothe throttle of the engine and an armature coil electromagneticallycoupled with said permanent magnet for producing an output voltageresponsive to the movement of said permanent magnet; first circuit meansconnected between said armature coil and second circuit means forrectifying said output voltage of said armature coil and supplying acurrent depending on said rectified output voltage to said secondcircuit means when said output voltage, exceeds a predetermined level;said second circuit means having a capacitor adaptable to storeelectricity by said current supplied thereto and a resistor adaptable todischarge said stored electricity for producing a voltage variablesignal with discharging of said stored electricity; pressure signalgenerating means responsive to the pressure of engine intake manifold ofsaid engine for generating a voltage signal indicative of said pressure;third circuit means connected to said second circuit means and saidpressure signal generating means and including an operational amplifierto add the signal derived from said second circuit means to the signalderived from said pressure signal generating means to produce a signalwhich varies as a function of the superposition of said voltage variablesignal produced by said second circuit means and said voltage signal ofsaid pressure signal generating means; fourth circuit means connected tosaid third circuit means for producing a fuel injection pulse signalwhose pulse width is determined by said signal produced by said thirdcircuit means; fifth circuit means connected to said fourth circuitmeans and said electromagnetic means for driving said electromagneticmeans for an interval corresponding to the pulse width of said fuelinjection pulse signal.
 2. An electrical fuel injection control systemfor an internal combustion engine comprising: a signal generator havinga member movable in response to the operation of the throttle and meansresponsive to the movement of said member for producing a first signalvoltage indicative of the moving speed of the throttle; first circuitmeans having a rectifier connected to said signal generator, a capacitorconnected to said rectifier to store electricity supplied theretothrough said rectifier by said first signal voltage of said signalgenerator, and a variable resistor connected in parallel with saidcapacitor for discharging said stored electricity, said rectifier havinga predetermined forward breakdown voltage whereby said first signalvoltage is applied to said capacitor only when said signal first voltageexceeds said forward breakdown voltage; means for detecting thecondition of the engine for producing a second signal voltage indiCativeof at least one predetermined parameter of the condition of said engine;means connected to said capacitor of said signal generator and saiddetecting means and including an amplifier having an operationalamplifier for adding the signal derived from said signal generator tothe signal derived from said detecting means; means connected to saidoperational amplifier for generating a fuel injection signal whose pulsewidth is controlled as a function of the addition by said operationalamplifier; and means connected to said fuel injection pulse signalgenerating means and having electromagnetic valves for injecting fuelinto cylinders of the engine in a predetermined sequence for an intervalcorresponding to said controlled pulse width of said fuel injectionpulse signal.
 3. An electrical fuel injection control system accordingto claim 1, wherein said fourth circuit means comprises a saw tooth wavegenerator.
 4. An electrical fuel injection control system according toclaim 2, wherein said fuel injection signal generating means comprises asaw tooth wave generator.